The field of the invention is camera cranes and remote control systems for use with camera cranes. Camera cranes are often used in motion picture and television production. The motion picture or television camera is typically mounted on a crane arm supported on a mobile base, dolly, or truck. The mobile base may be pushed and steered by hand. Larger units, which have more weight carrying capacity, and longer reaches, typically have electric driving motors powered by onboard batteries. Some mobile bases may also serve as over the road vehicles.
Camera cranes generally have a crane arm supported on a base, with a camera platform at one end of the arm, and a counter weight at the other end. The crane arm can be pivoted by hand to raise and lower the camera, and also to pan to the left or right side. A leveling system is often included to maintain the camera platform in a level orientation, as the camera platform is raised and lowered.
With the development of high definition digital, television cameras, and remote controlled motion picture cameras, filming can be achieved with or without a camera operator behind the camera. Rather, the remotely-controlled camera may be suspended on a crane arm, with the camera operator monitoring the image captured by the camera via a remote monitor, rather than a view finder in the camera. With the camera operator, cinematographer, director, etc. directly behind the camera, and with the camera controls, (focus, iris, zoom, etc.) and view-finder readily accessible directly, camera operations may be readily achieved with well known techniques which have been in use for many years. However, with remote control cameras, as the camera is not accessible to the camera operator (because, e.g., the camera is on a camera crane platform), controlling the camera requires different techniques. Video cameras and monitors allow the camera operator to monitor camera settings and positions, and can provide a remote view finder. Camera lens angles and positions, such as pan, tilt, and dutch have been controlled using electrically remote controlled motors or actuators moving a camera platform or tilt/pan head supporting the camera. While these types of control techniques have performed with varying degrees of success, challenges remain in view of the demanding requirements of motion picture or video production. For example, the remote control movement of the camera typically must be smooth, precise and without play or backlash, precisely repeatable, silent, and versatile in terms of speeds and ranges of movement.
Accordingly, it is an object of invention to provide an improved remote camera control system and accessory.
Even with the advent of remote control systems, most filming is still performed with the camera operator, cinematographer, director, or other person behind the camera, so that the recorded image is viewed in the view-finder of the camera, and not on a remote monitor.
Due to the variety of filming or video locations, the camera crane arm should advantageously be portable and lightweight. On the other hand, the arm must be rigid enough, when assembled, to resist bending and sagging, and to avoid excessive whipping motion of the camera during crane arm movement.
Mobile bases with crane arms supporting a camera are frequently also used in the television production of sporting events, concerts, and other televised or filmed events. While various camera cranes have been widely known and successfully used, certain disadvantages remain. One disadvantage is that the presence of the crane structure around the camera can interfere with the camera operator, cinematographer, director, etc., e.g., by preventing them from taking a desired position, usually behind the camera. Another disadvantage is the time required to set up a camera crane. Typically, camera cranes are provided in sections which must be bolted together to make a boom arm of a desired length. This requires time, tools, and skill. As production time is usually extremely expensive, even small time savings may be significant.
Accordingly, there is a need for an improved camera crane. There is also a need for an improved camera crane which is light weight and easily transportable, but yet which can steadily carry significant payloads, and which can position and support a camera in a wide range of positions and orientations, while also avoiding excessive interference with the camera operator. There is a further need for a camera crane which can be quickly and easily set up, preferably without the need for tools.
In a first aspect of the invention, a remote control system for controlling movement of a camera platform on a camera crane includes a shaft gear attached to a shaft extending from the camera platform. A motor in a drive accessory attachable to the camera crane turns the shaft gear, to move the camera platform e.g., in a pitching up/down, panning left/right, or rolling clockwise/counterclockwise. The drive accessory preferably has a worm gear on a motor shaft extending out of the motor, with the worm gear engaging the shaft gear. Advantageously, a spring acts to keep the worm gear engaged with the shaft gear.
In a second and separate aspect of the invention, a clutch limits the torque which may be exerted on the shaft gear. The clutch allows the shaft gear to slip relative to the camera platform, when a predetermined level of torque is exceeded. Consequently, the potential for damage to the gear and other components resulting from bumping (or other large unexpected forces on the camera platform), is reduced. Preferably, the clutch includes a tensioning bolt which compresses a spring acting on one or more pressure plates pressing against the shaft gear. A tension limiter is preferably included to limit the maximum amount of torque which can be exerted on the shaft gear via the clutch.
In a third and separate aspect of the invention, remote control movement of a camera platform on a camera crane is provided by an accessory which is attached to the crane, to provide for remote control movement, and which is removed from the crane, when not in use by (e.g., when the camera platform is moved or positioned by hand). The accessory advantageously includes a shaft gear rotatably supported in an accessory housing. When the accessory is installed, the shaft gear is connected to the camera platform, preferably via an accessory shaft extending out of the housing and connected to the camera platform. A drive motor gear, preferably a worm gear, is engaged with the shaft gear, and driven by a drive motor within the housing. The accessory housing is preferably pivotably attached to the crane, or a frame on the camera crane, with a spring urging the accessory housing in a direction to engage the drive motor gear with the shaft gear. A remote control box may be linked to the drive motor by a cable, to provide control signals and power from a remote location. Alternatively, control signals may be provided to the drive motor by a wireless link, and power provided by batteries on the camera crane. The remote control box preferably includes a precision control joystick which allows for a full range of movement, but with precise control.
In a fourth and separate aspect, a camera crane includes a boom arm pivotally connected to a post assembly adapted to be supported on a camera dolly. A track section is attached at the front end of the boom arm, and a counter weight platform is attached at the back end of the boom arm. Leveling rods extending between the track section and counter weight platform to maintain the track section and counter weight platform in a horizontal orientation, as the boom arm is pivoted or tilted up and down, to change the elevation of the camera. A camera frame is linearly movable along the track section. As a result, the camera can be easily moved into a wide range of positions.
In a fifth and separate aspect of the invention, the boom arm has a joggle section, to provide additional head room clearance around the camera.
In a sixth and separate aspect of the invention, the camera frame is rotatably supported on the track section, so that the camera can pan continuously in either direction, clockwise or counter-clockwise.
In a seventh and separate aspect of the invention, a camera platform is pivotally or rotatably attached to the camera frame. The camera is attached to the camera platform. As a result, the camera can continuously change elevation angle, with the camera lens positioned, e.g., vertically straight up or straight down, and at any angle in between.
In an eighth and separate aspect of the invention, and counter weight platform and counter weights are concave with a rounded back surface, to minimize the clearance space needed to turn the boom arm, while providing an extended range of camera lens height.
In a ninth and separate aspect of the invention, and anti-backlash or motion control pivot joint or device is provided on the boom arm and camera frame, to provide for smooth dampened back lash free movement.
In a tenth and separate aspect of the invention, a lightweight one piece camera crane is provided which can be quickly set up without tools.
In an eleventh and separate aspect of the invention, a track section on the crane can be quickly removed and replaced with an accessory to provide different camera mounting positions and a more compact and lightweight design.
In a twelth and separate aspect of the invention, roll movement is provided via an alternative camera frame design or via a roll movement accessory attached to a camera a base plate supported by the crane.
The invention resides as well in sub combinations of the features as described below. Additional features and advantages will appear hereinafter.